D3 point group

The empirical rule for the assignment of absolute configurations of D3 point group metal complexes of d3 or d6 electronic configuration may be applied (27). Accordingly, the low energy E transition will be positive for a A complex. 

Molecules belonging to the D3 point group are optically active. 

Finally fhe fixafion of fhe fhird ligand to give [Eu2(L13%] further involves an intramolecular cormection leading to a macrobicyclic complex (Eq. (103)). It is worth noting that [Eu2(L13 )a] is a chiral molecule (D3 point group), which exists at equilibrium as a racemic mixture. Its symmetry number must be divided by two to account for the entropy of mixing of the two enantiomers (Figure 85, Ercolani et al., 2007). 

No centre of symmetry or planes of symmetry have been identified and this confirms that molecular species in the D3 point group are chiral. 

By referring to the character table (Appendix 3) for the D3 point group, confirm that the symmetry elements of the Dj point group do not include i, cr or S axis. 

Solution, (a) PF5 is nonpolar (trigonal bipyramidal, 031, point group), (b) Co(en)3 + is nonpolar (D3 point group), (c) c/s-Dichloroethene is polar (C2V point group), (d) The boat form of cyclohexane is polar (C2V point group). 

Solution. Using the B-H bond vectors as basis sets for the generation of a representation in the D3(, point group, we obtain the results shown in the table. 

Bicyclo[2.2.2]octane (C) is unique among the four structural elements. It exhibits some flexibility and adopts a twisted conformation in the GS (D3 point group symmetry) with the twist angle calculated at about 17° (MP2/6-31G(d)). Therefore, most of its derivatives lack symmetry and consequently all conformers are chiral. 

The structures of fullerene Isomers suggested by the C NMR measurements, (a) Three isomers of C7S fullerene with C, C2v, and D3 point group, (b) Three structural candidates for Cs2 fullerene with C2 symmetry, (c) Structures of and C2v-Cs2 isomers (The picture was reprinted by permission from Macmillan Publishers Ltd. Nature, ref. Kikuchi et al. (1992a), copyright 1992)... 

---